波列振幅衰减测桩法的研究与应用(Ⅱ)——桩身成型质量的检测
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摘要
通过对波动、振动和尾波的特征分析,提出以足够大的力冲击桩顶,在桩顶附近记录综合波列图,利用其振幅衰减、周期变化和反射波震相等判断桩身成型质量:波列周期均匀且较小,同时波列振幅衰减较快,而又未见明显反射波震相者桩身成型良好;而有缺陷如断裂、缩径等时波列振幅衰减变慢,反射波震相明显,且有大周期出现.它对桩的浅部(特别是桩顶下5米以内的)缺陷检测特别有效.另外利用动态PS曲线也可判断桩身成型质量:曲线较平滑者,桩身成型良好;曲线出现弯折者桩身存在缺陷,缺陷程度可参照承载力受影响大小确定.
From analyzing characteristic of wave and vibration and coda we take a new methods by which quality of pile is evaluated. Quality of pile will be excellent if period of train is equality and small, and attenuation of amplitude is more quickly, and there is not phase of reflect-wave; There are defects (for example it occurs fracture or diameter become smaller) in the pile if attenuation of amplitude is slower, and the period of train is bigger much, and there is phase of reflect-wave for wave train recorded at top of pile by single impacting. This is especially efficiency for determining defects under top of pile 5 m. Otherwise quality of pile is evaluated by dynamic PS-curves. Quality of pile will be excellent if PS-curve is more smooth. There are defects in the pile if PS-curve is zigzag and twist. Of course, degree of defect is confirmed by decreasing amount of bearing capacity.
From analyzing characteristic of wave and vibration and coda we take a new methods by which quality of pile is evaluated. Quality of pile will be excellent if period of train is equality and small, and attenuation of amplitude is more quickly, and there is not phase of reflect-wave; There are defects (for example it occurs fracture or diameter become smaller) in the pile if attenuation of amplitude is slower, and the period of train is bigger much, and there is phase of reflect-wave for wave train recorded at top of pile by single impacting. This is especially efficiency for determining defects under top of pile 5 m. Otherwise quality of pile is evaluated by dynamic PS-curves. Quality of pile will be excellent if PS-curve is more smooth. There are defects in the pile if PS-curve is zigzag and twist. Of course, degree of defect is confirmed by decreasing amount of bearing capacity.
引文
[1]徐攸在,刘兴满.桩的动测新技术[M].北京:中国建筑工业出版社,1989.
[2]中国工程建设标准化协会标准.锤击贯入试桩法规程CECS35:91[M].中国建筑科学研究院,1991,刘金砺主编,桩基工程检测技术(附录).北京:中国建筑材工业出版社,1993.
[3]SmithEA.Pile drivingAnalysisbytheWaveEquation[A].PriceedingsASCE,August,1960.
[4]GobbleGG,etal.BearingCapacityofpilefromDynamic Mearsurements[R].FindReport,CASEWesternReserveU niversity,Cleveland,OhioUS,1975.
[5]RauscheF,GobleGG,LikinsE.DynamicDeter minationof PileCapacity[J].JGeotechnicalEngineering,ASCE,1985,111(3):367～383.
[6]CAPAWAP/CDescriptionandDevelopment[A].PDAUsers Day.Stockholm,Sweden,1984.
[7]RauscheF.CAPWAP/CPrinciplesandlimitations[M].Goble RauscheLinkinsandAssociates,IncApr,1986
[8]AkiK.Analysisoftheseismiccodaoflocalearthquakesas scatteredwaves[J].JGeophysRes,1969,74:615～631.
[9]GaoLS,LeeLC,BiswasNN,AkiK.Comparisonofthe effectsbetweensingleandmultiple scatteringoncodawavefor localearthquakes[J].BullSeismSocAmer,1983,73:377—389.
[10]高龙生,华正兴,李瑞.用尾波的强度和衰减估算北京地区S波的平均自由程[J].地震学报,1987,9(4):347～362.
[2]中国工程建设标准化协会标准.锤击贯入试桩法规程CECS35:91[M].中国建筑科学研究院,1991,刘金砺主编,桩基工程检测技术(附录).北京:中国建筑材工业出版社,1993.
[3]SmithEA.Pile drivingAnalysisbytheWaveEquation[A].PriceedingsASCE,August,1960.
[4]GobbleGG,etal.BearingCapacityofpilefromDynamic Mearsurements[R].FindReport,CASEWesternReserveU niversity,Cleveland,OhioUS,1975.
[5]RauscheF,GobleGG,LikinsE.DynamicDeter minationof PileCapacity[J].JGeotechnicalEngineering,ASCE,1985,111(3):367～383.
[6]CAPAWAP/CDescriptionandDevelopment[A].PDAUsers Day.Stockholm,Sweden,1984.
[7]RauscheF.CAPWAP/CPrinciplesandlimitations[M].Goble RauscheLinkinsandAssociates,IncApr,1986
[8]AkiK.Analysisoftheseismiccodaoflocalearthquakesas scatteredwaves[J].JGeophysRes,1969,74:615～631.
[9]GaoLS,LeeLC,BiswasNN,AkiK.Comparisonofthe effectsbetweensingleandmultiple scatteringoncodawavefor localearthquakes[J].BullSeismSocAmer,1983,73:377—389.
[10]高龙生,华正兴,李瑞.用尾波的强度和衰减估算北京地区S波的平均自由程[J].地震学报,1987,9(4):347～362.
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